Loans and Allowance for Loan Leases - Impaired Loans (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Recorded Balance
Total	$ 108,434	$ 93,500
Unpaid Principal Balance
Total	124,424	101,500
Specific Allowance	6,090	22,298
Commercial
Recorded Balance
Loans without a specific valuation	60,048	35,846
Loans with a specific valuation	11,935	35,030
Total	71,983	70,876
Unpaid Principal Balance
Loans without a specific valuation	60,077	35,846
Loans with a specific valuation	23,341	40,030
Total	83,418	75,876
Specific Allowance	3,228	19,942
Energy
Recorded Balance
Loans without a specific valuation	3,462	2,864
Loans with a specific valuation	12,241	6,880
Total	15,703	9,744
Unpaid Principal Balance
Loans without a specific valuation	7,741	2,864
Loans with a specific valuation	12,241	9,880
Total	19,982	12,744
Specific Allowance	1,224	1,949
Commercial real estate
Recorded Balance
Loans without a specific valuation	8,492	9,464
Loans with a specific valuation	6,348	1,028
Total	14,840	10,492
Unpaid Principal Balance
Loans without a specific valuation	8,622	9,464
Loans with a specific valuation	6,474	1,028
Total	15,096	10,492
Specific Allowance	1,449	210
Construction and land development
Recorded Balance
Loans without a specific valuation	0	0
Loans with a specific valuation	0	0
Total	0	0
Unpaid Principal Balance
Loans without a specific valuation	0	0
Loans with a specific valuation	0	0
Total	0	0
Specific Allowance	0	0
Residential real estate
Recorded Balance
Loans without a specific valuation	5,409	2,139
Loans with a specific valuation	245	249
Total	5,654	2,388
Unpaid Principal Balance
Loans without a specific valuation	5,430	2,139
Loans with a specific valuation	244	249
Total	5,674	2,388
Specific Allowance	189	197
Consumer
Recorded Balance
Loans without a specific valuation	254	0
Loans with a specific valuation	0	0
Total	254	0
Unpaid Principal Balance
Loans without a specific valuation	254	0
Loans with a specific valuation	0	0
Total	254	0
Specific Allowance	$ 0	$ 0